I am trying to PATCH (partially update) Firebase records (firebase.com). This works perfect outside of Google Apps Script using PATCH. GAS is not supporting PATCH and I tried X-HTTP-Method-Override without success. Using GAS with X-HTTP-Method-Override renders the same result as a standard GET. There is no security on my test database. No log-in is required.
var myPayload = "{\"WSD124\" : {\"auction\" : {\"stockno\" : \"ESD124\", \"highbid\" : \"240\"}}}";
var myURL = "https://mydatabase.firebaseio.com/auctions/.json";
var options = { headers: { "X-HTTP-Method-Override" : "PATCH" }, method: "POST", payload: myPayload };
var oResponse = UrlFetchApp.fetch(myURL,options);